<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        let number=1;
        function fun(){
            number++;
            if (number > 3){
                number = 1;
            }
            let imgLun = document.getElementById("img_lun");
            imgLun.src = `../img/banner_${number}.jpg`;

        }

        setInterval(fun,1000);

    </script>
</head>
<body>
<img src="../img/banner_1.jpg" alt="" id="img_lun"/>




</body>
</html>